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Neutron Design speculation
by
rakaydos
on 04 Mar, 2021 07:43
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Though this thread is a catch all for all aspects of Neutron's design, the big open question right now is the engine.
Rocket Lab is "still doing trade studies" on the engines, but with a NET only 4 years away, the possibility space is actually far more limited than it seems. There's not enough time to develop a new turbopump based engine from scratch, so RocketLab's options are limited to an existant turbopump engine bought from elsewhere (AR-1, Merlin, ect) or some kind of scaled up electrically pumped (or electrically turbo-pumped?) engine built in house that leverages their existing engine experience.
Please, nominate posts from the main Neutron thread to be moved here.
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#1
by
HVM
on 04 Mar, 2021 08:24
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It's needs to be shiny, so you can dangle it over potential after-SPAC-merger-investors.
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#2
by
Dmitry_V_home
on 04 Mar, 2021 13:21
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It's needs to be shiny, so you can dangle it over potential after-SPAC-merger-investors.
There are other potential suppliers of efficient rocket engines on the market. For example:
https://www.ursamajortechnologies.com/
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#3
by
jstrotha0975
on 04 Mar, 2021 13:51
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How difficult is it to scale an existing engine to the size RL would need?
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#4
by
Dmitry_V_home
on 04 Mar, 2021 14:32
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The history of SpaceX indicates that a company that has made a relatively small engine is able to increase its thrust several times in a short time. For Neutron, 9 engines in the first stage and one with a high-altitude nozzle in the second stage look reasonable. 60 tf
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#5
by
TrevorMonty
on 04 Mar, 2021 17:08
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RL shouldn't have any problems hiring talent they need to build new engine. There have been lot of turbopump engines in 5-550klbs range developed in last few years, which makes for large talent pool.
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#6
by
Davidthefat
on 04 Mar, 2021 18:06
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RL shouldn't have any problems hiring talent they need to build new engine. There have been lot of turbopump engines in 5-550klbs range developed in last few years, which makes for large talent pool.
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Key issue is if they want to keep the development of engines in New Zealand or not. I had insinuated a merger of RFA in Germany to get some talent from there in a previous post. If they want to develop in the USA, they need an all American team working on it with no or very minimal involvement from the Kiwi team due to ITAR. Which means hiring up a whole new division of propulsion engineers.
Look at the distribution of employees in the US vs New Zealand in the existing headcount.
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#7
by
TrevorMonty
on 04 Mar, 2021 20:57
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RL shouldn't have any problems hiring talent they need to build new engine. There have been lot of turbopump engines in 5-550klbs range developed in last few years, which makes for large talent pool.
Sent from my SM-T810 using Tapatalk
Key issue is if they want to keep the development of engines in New Zealand or not. I had insinuated a merger of RFA in Germany to get some talent from there in a previous post. If they want to develop in the USA, they need an all American team working on it with no or very minimal involvement from the Kiwi team due to ITAR. Which means hiring up a whole new division of propulsion engineers.
Look at the distribution of employees in the US vs New Zealand in the existing headcount.
I thought ITAR wasn't issue with NZ USA relationship. If it was I doubt they'd be flying DoD missions. RL would still need to careful which country they hire staff from, NATO countries should be issue.
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#8
by
Pueo
on 05 Mar, 2021 00:51
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RL shouldn't have any problems hiring talent they need to build new engine. There have been lot of turbopump engines in 5-550klbs range developed in last few years, which makes for large talent pool.
Sent from my SM-T810 using Tapatalk
Key issue is if they want to keep the development of engines in New Zealand or not. I had insinuated a merger of RFA in Germany to get some talent from there in a previous post. If they want to develop in the USA, they need an all American team working on it with no or very minimal involvement from the Kiwi team due to ITAR. Which means hiring up a whole new division of propulsion engineers.
Look at the distribution of employees in the US vs New Zealand in the existing headcount.
I thought ITAR wasn't issue with NZ USA relationship. If it was I doubt they'd be flying DoD missions. RL would still need to careful which country they hire staff from, NATO countries should be issue.
Sent from my SM-G570Y using Tapatalk
The agreement between the US and New Zealand basically has New Zealand enforcing the US ITAR regulations as if the ground the rocket sits on is magically US soil in return for the US allowing the export of ITAR covered products to New Zealand for the purpose of launch. That means that non US Persons don't get to inspect the ITAR components and can't have access to a location with the ITAR components without the supervision of a designated US Person.
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#9
by
Robotbeat
on 05 Mar, 2021 01:13
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That's fascinating. In that case, it's fair to call RocketLab a US launcher, IMHO, Ed Kyle.
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#10
by
rakaydos
on 05 Mar, 2021 13:27
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Moving this over from the main thread:
Except batteries don’t lose if you compare to some lower performance gas generators, like peroxide (even including the fact that the spent peroxide is dumped immediately overboard). Batteries are that competitive.
One alternative might be a dual GG approach where the GGs are essentially Rutherford engines running fuel rich. That might retain some of the development advantages where things like startup and shutdown sequencing can be controlled by software. Presumably similar simplifications are what motivated the peroxide fed GG on Soyuz. Is the peroxide pressure fed? Given it's just peroxide fed through a catalyst bed you start the engine by just opening a valve, simpler than starting a self-pumping GG with both pumps on a single shaft and the GG using those selfsame pumps. That seems like a hard bootstraps problem that adds significantly to the build-test-fix cycles.
That would have the added advantage of replacing TEA-TEB with batteries, a comparison that is undoubtedly considerably in the battery's favor. Seems like it might also simplify deep throttling.
Back of the envelope numbers for this.
Rutherford@SL is 3.05 km/s exhaust velocity and 25 KN thrust, meaning 8.2 kg/s propellant flow rate and about 38 megawatts raw thermal power. If you used a GG based on the Rutherford, assuming 0.2 efficiency and 0.5 combustion efficiency for fuel rich combustion, you're looking at about 4 megawatts power at the shaft. Using two such GGs per engine, with four engines, your overall battery requirement for the first stage is essentially the same as the existing Electron, and the overall pumping power assuming 2 per engine and 4 engines total is 32 megawatts. Which should be sufficient for 5+ meganewtons (>1 mlbf) thrust at liftoff. Which sounds about right for 8 tons to LEO.
No running out of TEA/TEB, more than enough electric power for electrically actuated aero surfaces.
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#11
by
ArbitraryConstant
on 05 Mar, 2021 16:13
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Another question, what's the upper stage engine(s) look like? If it's the same as the first stage and the first stage uses 4, that's probably overkill on thrust. If the first stage uses a non-electric or not purely electric cycle, Rutherford would incur a large battery penalty. If it's another new engine, that's another new engine they need to build (though commonality is probably possible if they're developed at the same time).
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#12
by
ArmyPaul
on 05 Mar, 2021 16:36
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The history of SpaceX indicates that a company that has made a relatively small engine is able to increase its thrust several times in a short time. For Neutron, 9 engines in the first stage and one with a high-altitude nozzle in the second stage look reasonable. 60 tf
Peter Beck revealed in an interview on the MECO podcast that despite the success of Electron's 9-engine design, he is not a fan of it moving forward with Neutron. He said Neutron will have fewer, larger engines and they are looking to accomplish powered descent through a combined approach of deep throttling and unique engine layout. He didn't get into specifics and admitted that they are somewhere between concept-level and solid design. Just based on his answers and how he approached the questions, it seems they are looking at an engine developed in-house based on lessons learned from Electron and the Rutherford engines. It certainly would go with his preferred approach to a vertically-integrated launch services provider.
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#13
by
Lars-J
on 05 Mar, 2021 17:04
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The history of SpaceX indicates that a company that has made a relatively small engine is able to increase its thrust several times in a short time. For Neutron, 9 engines in the first stage and one with a high-altitude nozzle in the second stage look reasonable. 60 tf
Peter Beck revealed in an interview on the MECO podcast that despite the success of Electron's 9-engine design, he is not a fan of it moving forward with Neutron. He said Neutron will have fewer, larger engines and they are looking to accomplish powered descent through a combined approach of deep throttling and unique engine layout. He didn't get into specifics and admitted that they are somewhere between concept-level and solid design. Just based on his answers and how he approached the questions, it seems they are looking at an engine developed in-house based on lessons learned from Electron and the Rutherford engines. It certainly would go with his preferred approach to a vertically-integrated launch services provider.
This means they will need to develop an engine that is at Merlin 1D level or greater. Doable (SpaceX did it), but on their schedule and budget?
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#14
by
Cheapchips
on 05 Mar, 2021 17:56
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The history of SpaceX indicates that a company that has made a relatively small engine is able to increase its thrust several times in a short time. For Neutron, 9 engines in the first stage and one with a high-altitude nozzle in the second stage look reasonable. 60 tf
Peter Beck revealed in an interview on the MECO podcast that despite the success of Electron's 9-engine design, he is not a fan of it moving forward with Neutron. He said Neutron will have fewer, larger engines and they are looking to accomplish powered descent through a combined approach of deep throttling and unique engine layout. He didn't get into specifics and admitted that they are somewhere between concept-level and solid design. Just based on his answers and how he approached the questions, it seems they are looking at an engine developed in-house based on lessons learned from Electron and the Rutherford engines. It certainly would go with his preferred approach to a vertically-integrated launch services provider.
This means they will need to develop an engine that is at Merlin 1D level or greater. Doable (SpaceX did it), but on their schedule and budget?
I'd assume that over the last 18mths they've come up with a good plan of how that can fit engine development within their $200m budget. Their 3d printing experience on Rutherford must count for something with regards to rapid development.
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#15
by
JEF_300
on 05 Mar, 2021 18:05
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I'll quote this post of mine here, just so that this quote from Beck is on this thread somewhere.
The new MECO podcast (https://mainenginecutoff.com/podcast/183) is an interview with Peter Beck. He said something that interested me while talking about the engine studies they're doing. The quote I transcribed here begins at 17:22
I don't like a whole bunch of engines. Having flown Electron for a long time now, nine engines is great if one stops; that's the only occasion that nine engines is great. Other than that, it's just nine times the amount of acceptance testing, nine times the amount of manufacturing, nine times the amount of everything.
Like I just said on the main thread, I suspect they'll end up settling on 3-4 engines in the end, as a compromise between the complexities of a big engine and difficulties of a bunch of smaller engines. That means you end up with an engine with a max thrust of, what, 750 to 1,300 kN?
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#16
by
Robotbeat
on 05 Mar, 2021 18:10
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4 engines and a landing engine (based on a beefed up Rutherford?) wouldn’t be terrible.
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#17
by
Lars-J
on 05 Mar, 2021 18:13
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I'll quote this post of mine here, just so that this quote from Beck is on this thread somewhere.
The new MECO podcast (https://mainenginecutoff.com/podcast/183) is an interview with Peter Beck. He said something that interested me while talking about the engine studies they're doing. The quote I transcribed here begins at 17:22
I don't like a whole bunch of engines. Having flown Electron for a long time now, nine engines is great if one stops; that's the only occasion that nine engines is great. Other than that, it's just nine times the amount of acceptance testing, nine times the amount of manufacturing, nine times the amount of everything.
Like I just said on the main thread, I suspect they'll end up settling on 3-4 engines in the end, as a compromise between the complexities of a big engine and difficulties of a bunch of smaller engines. That means you end up with an engine with a max thrust of, what, 750 to 1,300 kN?
Perhaps... But with 3 or 4 engines you are now looking at at engine closer to the size of Raptor and Be-4, certainly bigger than Merlin.
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#18
by
JEF_300
on 05 Mar, 2021 18:23
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I'll quote this post of mine here, just so that this quote from Beck is on this thread somewhere.
The new MECO podcast (https://mainenginecutoff.com/podcast/183) is an interview with Peter Beck. He said something that interested me while talking about the engine studies they're doing. The quote I transcribed here begins at 17:22
I don't like a whole bunch of engines. Having flown Electron for a long time now, nine engines is great if one stops; that's the only occasion that nine engines is great. Other than that, it's just nine times the amount of acceptance testing, nine times the amount of manufacturing, nine times the amount of everything.
Like I just said on the main thread, I suspect they'll end up settling on 3-4 engines in the end, as a compromise between the complexities of a big engine and difficulties of a bunch of smaller engines. That means you end up with an engine with a max thrust of, what, 750 to 1,300 kN?
Perhaps... But with 3 or 4 engines you are now looking at at engine closer to the size of Raptor and Be-4, certainly bigger than Merlin.
Well, with the Merlin 1D now at 850 kN and the Raptor at 2,200 kN, it's really hard to say it's closer to the size of Raptor.
But yeah, bigger engines. And when talking about 3 or 4 engines, you might not even have a center engine. All of which actually only makes me think that's we're getting closer to what their thinking about, because that would certainly qualify as, to quote something else Beck said, an "alternate configuration".
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#19
by
ArbitraryConstant
on 05 Mar, 2021 18:31
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4 engines and a landing engine (based on a beefed up Rutherford?) wouldn’t be terrible.
I think if they use four engines they'll use just one of them gimbaled way the hell over and land at an angle.